| 古特提斯洋俯冲碰撞在南羌塘的岩浆岩证据:西藏荣玛乡冈塘错花岗岩 |
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| 引用本文： | 李静超,赵中宝,郑艺龙,袁国礼,梁晓,王根厚,刘曦.古特提斯洋俯冲碰撞在南羌塘的岩浆岩证据:西藏荣玛乡冈塘错花岗岩[J].岩石学报,2015,31(7):2078-2088. |
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| 作者姓名： | 李静超 赵中宝 郑艺龙 袁国礼 梁晓 王根厚 刘曦 |
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| 作者单位： | 中国地质大学地球科学与资源学院, 北京 100083,中国地质大学地球科学与资源学院, 北京 100083,中国地质大学地球科学与资源学院, 北京 100083,中国地质大学地球科学与资源学院, 北京 100083,中国地质大学地球科学与资源学院, 北京 100083,中国地质大学地球科学与资源学院, 北京 100083,北京大学造山带与地壳演化教育部重点实验室, 北京 100871 |
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| 基金项目： | 本文受中国地质调查局项目(1212011086062、1212011221081、1212011221115)和国家自然科学基金项目(41090371、41372212)联合资助. |
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| 摘 要： | 西藏荣玛乡冈塘错花岗岩岩体分布于南羌塘地块中,由中粗粒巨斑状黑云母二长花岗岩和中细粒含电气石二云母二长花岗岩组成。中粗粒花岗岩的锆石测年结果为214.4±4.0Ma,中细粒花岗岩锆石测年结果为222.2±6.6Ma,均为晚三叠世。中粗粒花岗岩A/CNK为1.00~1.09,刚玉标准分子的百分含量均大于1%(1.84~3.04%),Al2O3的含量均大于14%,属于含白云母过铝质花岗岩。中细粒花岗岩的A/CNK1.1,刚玉标准分子的百分含量均大于1%(2.40~3.42%),Al2O3的含量均大于14%,属于强过铝质S型花岗岩。虽主量元素特征相近,但两类花岗岩的微量元素特征差异较大。根据锆石饱和温度计得出中粗粒花岗岩为高温类型的花岗岩,中细粒花岗岩为低温类型的花岗岩。结合区域地质背景推断中细粒花岗岩形成可能与三叠纪俯冲碰撞作用有关,而中粗粒花岗岩为碰撞后拆沉岩浆底侵的结果。冈塘错岩体中两种成因类型不同的花岗岩的形成时代对古特提斯洋的演化以及缝合带增生杂岩的形成具有时代约束意义。
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| 关 键 词： | 古特提斯洋 南羌塘 俯冲碰撞 冈塘错花岗岩 晚三叠世 西藏 |
| 收稿时间： | 2014/9/16 0:00:00 |
| 修稿时间： | 2014/12/26 0:00:00 |
The magmatite evidences in southern Qiangtang for paleo-Tethys ocean subducting collision: Gangtang-co granites in Rongma, Tibet. |
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| LI JingChao,ZHAO ZhongBao,ZHENG YiLong,YUAN GuoLi,LIANG Xiao,WANG GenHou and LIU Xi.The magmatite evidences in southern Qiangtang for paleo-Tethys ocean subducting collision: Gangtang-co granites in Rongma, Tibet.[J].Acta Petrologica Sinica,2015,31(7):2078-2088. |
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| Authors: | LI JingChao ZHAO ZhongBao ZHENG YiLong YUAN GuoLi LIANG Xiao WANG GenHou and LIU Xi |
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| Institution: | School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China and Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education of China, Peking University, Beijing 100871, China |
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| Abstract: | Gangtang-co granite rocks are located in Rongma of southern Qiangtang in Tibet. The rocks are composed of coarse-medium porphyritic biotite monzogranite and medium-fine tourmaline two-mica monzogranite. Dating of zircon was 214.4±4.0Ma for the former granite, and 222.2±6.6Ma for the latter. Both of them were at Late Triassic. The coarse-medium grained granite is muscovite peraluminous granite with following characteristics: 1.00~1.09 of A/CNK, >1% (1.84~3.04%) of calibrated corundum, and >14% of Al2O3. The fine-medium grained granite is peraluminous S-type granite with following characteristics: >1.1% of A/CNK, >1% (2.40~3.42%) of calibrated corundum, and >14% of Al2O3. Although being similar in major elements, the characteristics of trace elements in two granites were significantly different. According to the zircon saturation thermometer, the former should be high-temperature type granite while the latter being low-temperature type granite. Based on the geological background in central Qiangtang, the formation of fine-medium grained granite was proposed to be associated with the subducting collision in Triassic. After it, the coarse-medium grained granite was formed through magmatic underplating delamination. In Gangtang-co rocks, the ages of two types of granites provided time constraints for the evolution of paleo-Tethys and the formation of accretionary complexes in the suture. |
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| Keywords: | Paleo-Tethys Ocean Southern Qiangtang Subducting collision Gangtang-co granites Late Triassic Tibet |
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